As an industrial trend is fast changing to an IT industry, an environment friendly energy industry and an electric vehicle industry, the demand for a lithium secondary battery as a power device is greatly increasing. Moreover, as an electronic device becomes compact-sized, the development on a high output and high energy density active substance, which may substitute a conventional electrode material of a lithium secondary battery, is widely underway.
In case of an anode, a theoretical capacity of graphite used for most of commercial lithium secondary batteries is about 372 mAh/g, and an inter-layer spreading speed of lithium is slow, for which a high speed charging and discharging are limited. A silicon composite anode material is gaining a great attention, which may be used to resolve the aforementioned problem and have been as an active substance for the past 20 years, wherein the theoretical capacity thereof is about 4200 mAh/g. In case of a silicon-graphite composite anode material, the development thereon is intensively underway in the related industry for the sake of an actual commercialization; however there still is a limit when competing with a conventional graphite in terms of its manufacturing process cost even though a good energy density and an enhanced charging and discharging service life.
In order to resolve a mechanical damage to an electrode and a fast service life decrease problem when using a silicon, which occur due to a volume expansion and contraction as it is repeatedly charged and discharged, like most of metallic substances which are electrically and chemically alloyed with lithium, it needs to increase performance through a nano-sized particle preparation, a nano-structural configuration, a nano-composite configuration and a complexation with a lithium activation/deactivation hetero-material.
Most of the researches focused on the preparation of a nano-sized silicon anode are being carried out, mainly, based on a mechanical crushing and a complexation, a vapor synthesizing method, a solution-based chemical synthesizing method, etc. Good results on the characteristic of a secondary battery anode are being reported; however there still is a problem in the way that a complicated process involved in a synthesis, a high material cost, an input of impurities, a waste thing treatment cost, an oxide production which is inevitably entailed during a synthesizing process, which makes hard to actually use it as a material for commercialization.
The high energy plasma technology of an electric explosion is referred to a massive synthesis technology of powder, and it has been developed for a long time. In recent years, an in-liquid electric explosion technology with respect to a semiconductor material has been developed (an application number 10-2008-0126028), which shows that a silicon may electrically explode in liquid; however the silicon is oxidized into SiO2 in an aqueous solution, for which the silicon is not appropriate as an anode active substance for a lithium secondary battery.